This invention relates to an optical information recording medium provided thereon with a mark indicative of a reference position, particularly a recording medium of the type in the form of a card, and an information recording-reproducing apparatus for such a recording medium.
As the forms of a recording medium on which information is recorded by the use of a light and the recorded information is read out, there are known various types such as the form of a disc, the form of a card and the form of a tape. Among these, an optical information recording medium in the form of a card (hereinafter referred to as the optical card) has a great expected demand as a compact, light-weight and readily portable medium of great recording capacity.
Referring to FIG. 1 of the accompanying drawings which is a schematic plan view of an example of such an optical card, reference numeral 101 designates the optical card, reference numeral 103 denotes tracking tracks, and reference numeral 107 designate areas in which track numbers are recorded.
The card is scanned by a light beam modulated in accordance with recording information and stopped down into a minute spot, whereby information as a row of optically detectable recording pits (information tracks) is recorded on the optical card.
In order that at this time, information may be accurately recorded and reproduced without the trouble of intersection between information tracks being caused, the position of application of the light beam must be controlled in a direction perpendicular to the scanning direction (auto-tracking, which will hereinafter be referred to as AT). Also, in order that the minute spot may be stably applied in spite of the bending and mechanical error of the optical card, control must be effected in a direction perpendicular to the surface of the optical card (auto-focusing, which will hereinafter be referred to as AF).
A recording-reproducing method will now be described with reference to FIG. 1. Initially, the light beam lies at the home position outside the recording area. The light beam is then moved relative to the optical card 101 in the direction of arrow D to find a track to be recorded or reproduced, and scans this track in the direction of arrow F, thereby effecting recording or reproduction. Here, as means for detecting whether that track is a desired track, track numbers 107 (hereinafter referred to as the pre-format) pre-recorded on the extensions of the tracking tracks 103 as illustrated in FIG. 2 of the accompanying drawings are read and the read content is inspected to thereby determine whether the track is the desired track. Also, by making reference to the track number and the control information, whether that track is recorded can be known and thus, so-called overwriting, which means that information is further written on the recorded track by mistake, can be prevented.
In such an optical card, however, the tracking tracks which should not originally be discontinuous become partly discontinuous in the track number portion, and this provides disturbance to the AT control- circuit system, which is undesirable in control. Also, track addresses as information data are preformed and therefore, where there is a defect such as a pin-hole at the location whereat this track number is formed, there has been a problem that malfunctioning occurs when the track number as data is read.
So, it would occur to mind to preform only tracking tracks on the recording medium instead of preforming addresses on the recording medium. In this case, however, there is a problem that when a desired recording portion is sought after, the spot fails to follow the desired track in the edge portion or goes beyond the final track and deviates from the surface of the medium.
On the other hand, the recording speed and reproducing speed of the optical information recording medium will be more and more improved by advancement in the future. Also, various modulation and demodulation systems will be adopted depending on how the medium is used. In the prior-art mediums, the aforementioned point has not been taken into account, and this has led to a disadvantage that it is difficult to secure mutual interchangeability in high-degree applied systems.
A first object of the present invention is to eliminate the aforementioned disadvantage regarding the formation of track addresses and to provide an optical information recording medium in which confirmation of a reference position can be reliably accomplished by a simple construction and overwriting can be avoided.
A second object of the present invention is to provide a recording-reproducing apparatus for such an optical information recording medium.
A third object of the present invention is to further eliminate the aforementioned disadvantage regarding the mutual interchangeability and to provide an optical information recording medium of simple construction which can also be used with high-degree systems which handle a plurality of types of mediums.
The first object of the present invention is achieved by an optical information recording medium which has tracking tracks arranged at intervals and recording portions provided between said tracking tracks and on which information is recorded by application of a light beam thereto, and in which an optically detectable mark indicative of a reference position is provided at at least one location in at least one of said recording portions.
The second object of the present invention is achieved by an information recording-reproducing apparatus having a light source, lens means for imaging the light beam from the light source on a recording medium, a photodetector for receiving the light from the recording medium, detector means for detecting a reference position mark on the recording medium on the basis of the signal from the photodetector, means for beginning auto-tracking on the basis of the signal from the detector means, and means for controlling a tracking actuator on the basis of the signal from the detecting means to start recording and reproduction of information from a predetermined position on the recording medium.
The third object of the present invention is achieved by an optical information recording medium which has tracking tracks arranged at intervals and recording portions provided between said tracking tracks and on which information is recorded by application of a light beam thereto, and in which an optically detectable mark indicative of the type of the medium is provided at at least one location on said recording portions.
Other objects and features of the present invention will become apparent from the following detailed description of the embodiments thereof taken in conjunction with the accompanying drawings.